'Another New Mars': NASA Orbiter Ready for Red Planet Science

This enhanced-color view shows gullies in an unnamed crater in the Terra Sirenum region of Mars. It is a sub-image from a larger view imaged by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter on Oct. 3, 2006. This scene is about 254 meters (about 830 feet) wide.Credit: NASA/JPL/Univ. of Arizona.

NASA's latest
spacecraft to orbit Mars has already
found new clues to the red planet's changing environment, and the best is yet
to come, mission managers said Monday.

The Mars
Reconnaissance Orbiter (MRO) is still weeks away from beginning its planned
science mission, but the immense probe has thrilled scientists with initial
images and data pointing to a variable polar environment, ancient soaking
events that produced clays, and relatively new--geologically speaking--gullies
carved into the shadowed rim of a southern crater.

"We have
another new Mars," said Steve Saunders, MRO program scientist at NASA's
Washington D.C. headquarters, in a mission briefing. "Every time we go to Mars
with a new set of instruments, we see a different planet."

Over the
last two weeks, Mars researchers tested MRO's complex suite of instruments. During
the instrument checks the MRO instruments found evidence of changes at Mars'
north polar ice cap, as well as relatively young gullies, mission scientists
said.

"During our
check-out period we were deliberately picking places that we knew about and
that would help us in our [instrument] calibration," said NASA's Rich Zurek,
MRO project scientist at the Jet Propulsion Laboratory (JPL) in Pasadena, California. "Now we're going to find new areas as well."

MRO used
its imaging spectrometer to examine a 3,500-foot (1,066-meter) cliff in Chasma
Boreale, an expansive valley that juts into Mars' northern polar ice cap. The
orbiter found a cap of ice covering atop a series of layers that alternate
between ice-rich and dust-rich bands, suggesting relatively recent
environmental and climate changes.

"At the
north polar ice cap over the last 100,000 or so years, there's been a really
dynamic history of changes reported in layers of ice much like we would
determine Earth's climate change and looking at a core of ice from Greenland,"
said Scott Murchie, of Johns Hopkins University's Applied Physics Laboratory,
who serves as lead scientist for MRO's imaging spectrometer.

The imaging
spectrometer also spied a wide range of mineral-rich clays on Mars in a region
known as Mawrth Valles; some rich in iron while others nearby contained
aluminum.

"Clay tells
us that the surface was wet, and differences in the mineralogy tells us how the
environment may have been different from place to place," Murchie said, adding
that differences in clay composition can indicate variations in water
temperature, salinity and other characteristics in the site's past. "What this
is telling us is that on length scales of just a few hundred yards, the
conditions were varying significantly enough that entirely different kinds of
minerals were forming."

MRO's High
Resolution Imaging Science Experiment (HiRISE) camera--an all-seeing eye so
powerful it can resolve objects the size of people and recently
photographed the NASA rover
Opportunity on the rim of Victoria Crater [image]--also
found evidence of channels around Mawrth Valles to support its ancient watery
history, researchers said.

HiRISE also
photographed a series of young gullies etched into the shadowed, frost-ridden
wall of an unnamed Martian crater in the Terra
Sirenum region.

"What
impresses me most is that this is really a system of gullies, this is a complex
landform," said Alfred McEwen, HiRISE principal investigator at the University
of Arizona, adding that they may have been carved by flowing water in the past.
"The big question here is, 'Is water seeping to the surface today?' and right
now we don't have a smoking gun."

MRO has
been circling Mars since it arrived
at the red planet in March, but only settled into its final
science orbit last month. Launched
on Aug. 12, 2005, the spacecraft carries enough fuel to last through 2018. Full
science operations will begin Nov. 7 after the red planet has passed behind the
Sun.

The orbiter
is expected to add new chapters to the story of Mars' watery history and help
scientists identify potential landing sites for future red planet missions.

"We're just
at the start of our data acquisition period and it's a little daunting to think
that, very soon, we'll be opening up a fire hose of data from the spacecraft,"
Zurek said. "Our appetites are whetted and we're excited to get started."